weird scaling (old raids)

[Lamiara]

I regularly do old raids and world bosses on a variety of characters, and this week I noticed that those still 110 (measly geared, btw) have an easier time than 115+ level characters.
The 110s finish the bosses faster. Keep in mind this is old content, so no idea what is up with this weird scaling.

Can anyone confirm?
Should I rather *not* level any characters if my main goal is derping around in old content?

[Tankperson]

I've found it just as easy on my 120's then on any other toons. Yes might take a second or two longer then before the xpac but still no problem at all.

[Lamiara]

nevermind, found out it's due to class disparity.
Some classes suck even at 120, while others deal the same amount of damage or more at 110 already lol.

The scaling is off too at times, but not that much that it is a reason to refrain from leveling.